Orthodontic appliance with porous tooth-abutting face

ABSTRACT

Attachment of an orthodontic appliance by direct bonding to a tooth utilizing a composite base with a porous tooth-abutting face and various methods for making the device, such as casting as a unitary structure, or forming the composite base by rolling a mesh, in strip form, so as to form flats on at least one surface of the mesh where the mesh is to be in contact with a solid base portion, then bonding the mesh to the base. In the latter embodiment, the metal base is a metal foil to which the appliance is attached and the mesh and foil form a composite strip, from which individual composite pads are formed.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of U.S. Patent Application Ser. No.802,011, filed June 1, 1977, now U.S. Pat. No. 4,068,379, issued Jan.17, 1978, which application is a continuation-in-part of pending U.S.Patent Application Ser. No. 779,056, filed Mar. 18, 1977, whichapplication is a continuation-in-part of U.S. Patent Application Ser.No. 677,412, filed Apr. 15, 1976, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to devices for the attachment of an orthodonticappliance to a tooth and methods for making such a device.

2. Description of the Prior Art

The well-known practice of using bands to secure orthodontic appliancesto the teeth is not generally desirable because bands create spacesbetween the teech which must be closed at the conclusion of theorthodontic treatment. A bracket made of plastic and bonded directly tothe tooth has been utilized for attachment of an orthodontic appliancedirectly to the tooth, thereby eliminating the band, as is shown in U.S.Pat. No. 3,303,565. Even though a plastic bracket bonds well to a tooth,such brackets have not generally provided the structural strength andcontrol required for many types of orthodontic treatment. Thus, metalbrackets fixed to composite metal and flexible plastic bases have beenused in attempting to provide greater rigidity, as shown, for example,in U.S. Pat. No. 3,250,003.

A series of openings through a base pad, either metal, U.S. Pat. No.3,932,940, or plastic, U.S. Pat. No. 3,765,091, on to which anorthodontic appliance is mounted, have been utilized with a suitablecement to help retain and bond the pad to the tooth. The holes allow thecement to flow into the openings to provide additional mechanicalstrength to the bond between the pad and the tooth. However, suchplastic bases suffer from a lack of rigidity although providing goodbonding, while such metal bases suffer from weak bonding while providinggood rigidity. In both instances, the cement flows through the holesinto the orthodontic appliance when being bonded to the tooth. Thecement can not be immediately removed, because attempting to do so wouldmove the device while the cement is curing, thereby negating the precisepositioning required for orthodontic treatment. However, if theorthodontist waits to remove the excess cement from the appliance untilthe pad is reasonably securely bonded to the tooth, the cement hasalready bonded itself to the appliance, and therefore is difficult toremove.

Another base of this type is a pad of metal screen or mesh, to which theorthodontic appliance is attached by spot welding. Such devices,currently sold by American Orthodontics, Sheboygan, Wis., suffer from aweak attachment of the appliance to the pad, as well as not providingthe strength of bonding of a plastic base or the rigidity of a metalbase, and permitting an even greater amount of cement to pass throughthe base pad and contact the appliance. In a modified type of such adevice, also sold by American Orthodontics, the appliance is mounted ona metallic base pad, which may be either plain or perforated, to which apad of metal screen or mesh is attached by spot welding, so as to fixthe screen to the base pad on the side of the pad opposite theappliance. Such a device, if not perforated, avoids the problem ofexcess cement flowing into the appliance by shielding the appliance fromthe cement, which must flow outwardly from the periphery of the pad, notthrough it. However, the spot welds destroy the mesh structure at thepoints of attachment of the screen to the pad, thereby decreasing theeffectiveness of the adhesive in bonding the mesh to the tooth. Becauseof the flexible nature of the screen, many spot welds are necessary toensure rigidity of this type composite pad, so that the mesh is not veryeffective. Alternatively, if only a few spot welds are utilized, themesh flexes so that the effectiveness of the appliance in theorthodontic treatment diminishes.

SUMMARY OF THE INVENTION

According to the present invention, an orthodontic appliance is attachedto a tooth by means of a base having a composite cross-sectionalconfiguration with a porous or mesh-like tooth-abutting face whichpermits the tooth bonding adhesive to enter into but not pass throughthe base. In one embodiment, the base is a unitary structure, with theporous face formed by casting, chemical etching, or similar processeswhich will provide cavities, recesses, woven interstitial spaces or thelike in the tooth-abutting face, hereinafter generally referred to asbeing "porous." When in use, an orthodontic appliance extends outwardlyfrom the base opposite the porous face. The appliance may be separatelyattached to the base by welding, brazing, soldering or the like, or thebase and appliance may be a single integral part, in which case, thebase, including the porous face and appliance preferably are castsimultaneously by the porous face portion being fixed to or formed inthe remainder of the base during the casting operation. In anotherembodiment, a composite base for direct attachment of an orthodonticappliance to a tooth is formed by a separate mesh portion which isbonded to a metal base portion at each interface between the mesh andthe base. In the preferred such embodiment, prior to bonding, pressureis applied to the mesh, either in or out of contact with the basematerial, to provide a greater area of contact or interface between themesh and the base during the bonding process by forming flats on thesurfaces of the mesh which interface with the base. While various knownprocesses can be utilized to produce the bond, such as diffusion bondingand brazing, a diffusion bonding process is preferably used, duringwhich the temperature is kept below the flow temperature of the base andmesh materials, so that only the "flatted" surface of the mesh materialin direct contact with the metal base is bonded. Thus, the base materialdoes not flow into the interstices of the mesh, while a continuous bondis achieved by bonding each interface to the base.

Bases or pads, to which orthodontic appliances are to be attachedaccording to the invention in one of its aspects, preferably are formedfrom strips of the bonded mesh and metal foil base material by stampingor otherwise forming separate composite pads, preferably to conform toparticular tooth surfaces. The porous tooth-abutting meesh surface ofthe pad is adapted to attach the appliance carrying pad to the surfaceof a tooth by use of an adhesive. The particular orthodontic applianceis attached to the non-porous surface of the composite pad either by theorthodontist during treatment or during the manufacturing or otherprocessing of the pad. After preparing the surface of the tooth fordirect bonding in any well-known manner, the orthodontist appliesappropriate cement to the porous face, which is then fixed directly tothe tooth. Edgewise brackets, light wire brackets, or any other type oforthodontic device used in the art, may be attached directly to a toothby utilizing the present invention in any of its many variousembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may more readily be understood by referring to theaccompanying drawings, in which:

FIG. 1 illustrates a portion of a strip of composite bases or padsconstructed in accordance with the invention;

FIG. 2 is a side elevation of the pads of FIG. 1 taken along lines 2--2of FIG. 1;

FIG. 3 is a view, in section, taken along lines 3--3 of FIG. 1;

FIG. 4 illustrates a strip of composite pads according to an alternateembodiment of the invention;

FIG. 5 is a view, in section, taken along lines 5--5 of FIG. 4;

FIG. 6 is a view of another alternate embodiment of a strip of compositepads according to the invention;

FIG. 7 is a view, in section, taken along lines 7--7 of FIG. 6;

FIG. 8 illustrates a strip of composite pads according to anotheralternate embodiment of the invention;

FIG. 9 is a view, in section, taken along lines 9--9 of FIG. 8;

FIG. 10 is an isometric view of a portion of mesh for use in one generalembodiment of the invention;

FIG. 11 is a partial sectional view of a base and mesh portion of acomposite pad according to a particular embodiment of the invention;

FIG. 12 is a partial sectional view of a base and mesh portion accordingto another particular embodiment of the invention;

FIG. 13 is a view of a strip of composite pads formed by bonding thebase strip and mesh strip together and forming individual connected padshaving predetermined contours to compliment preselected tooth surfaces,showing the surface of the composite strip to which an orthodonticappliance is attached;

FIG. 14 is a view taken along lines 14--14 of FIG. 10 and illustratingthe mesh undersurface of the composite strip for adhesion to the toothsurfaces;

FIG. 15 is a view illustrating a base strip and a mesh strip for use inthe preferred embodiment of the invention;

FIG. 16 is a diagrammatic view of the base and mesh strips of FIG. 15during the step of applying pressure thereto to assist in the bondingprocess;

FIG. 17 is a cross-sectional view of an alternate embodiment oforthodontic appliance according to the present invention adapted to becast as a unitary structure;

FIG. 18 is a partial cross-sectional view of another embodiment of acast orthodontic appliance according to the present invention;

FIG. 19 is a partial cross-sectional view of a further alternateembodiment of cast orthodontic appliance according to the presentinvention; and

FIG. 20 is a fragmentary cross-sectional view of a modification of theembodiment of FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is shown a view of a portion of a stripof composite pad assemblies 10 constructed in accordance with thepresent invention. Each of the assemblies 10 has an orthodontic bracket12, of conventional construction, attached thereto. As shown in FIG. 1,the attachment of the bracket 12 to the pad 10 is at the base portion 13by means of a series of spot welds 14, shown in dotted lines in FIG. 1.The pads 10 are generally rectangular in shape, with rounded corners,and are connected together at the edges thereof by creased portions 16,so as to permit the facile separation of one pad from the next.

Referring now to FIG. 2, there is shown a view, taken along lines 2--2of FIG. 1, more clearly illustrating the construction of the compositepad strip. In FIG. 2, the composite pads 10 are seen to consist of anupper non-porous surface 18 and a lower porous tooth-abutting surface20. In the embodiment shown in FIGS. 1-3, the lower poroustooth-abutting surface 20 is a mesh or screen, such as 100 meshstainless steel terminating in the upper surface 18, which is preferablyof a fairly rigid foil, for example stainless steel of about 0.007 inchthickness. The upper and lower surfaces 18, 20 are bonded together atthe interfaces therebetween, that is, the individual points of contactof the mesh or screen 20 with the upper surface 18 (see FIGS. 11,12).Such bonding may be by sintering or diffusion bonding, brazing, or thelike, as is described hereafter. The pad 10 is seen to be shaped, uponcompletion of manufacture, so as to generally conform to the surfaceconfiguration of a particular tooth. Various pads will have variouscurvatures to correspond to the different curvatures of the differentteeth which may be subject to orthodontic treatment.

In FIG. 3, there is shown a view, in section, taken along lines 3--3 ofFIG. 1, which illustrates the curvature of the pad 10 and the relativedisposition of the foil or impervious surface 18 and the porous mesh orscreen surface 20.

FIG. 4 illustrates an alternate embodiment of the invention, being aview of a series of pad assemblies 10A. Each pad assembly 10A has abracket 12A which has a base portion 13A considerably larger than thebase portion 13 of the bracket 12 of FIGS. 1-3. Alternatively, thebracket 12A could be, if desired, a pair of individual brackets, such asis shown in U.S. Pat. No. 3,932,940, the brackets being directlyattached to a foil surface corresponding to the foil surface 18 of theembodiment of FIGS. 1-3. In FIG. 4, a series of pads 10A are connectedtogether at their edges 16A in the same manner as those shown withrespect to FIGS. 1-3.

FIG. 5 is a sectional view taken along lines 5--5 of FIG. 4 illustratingthe same attachment of mesh surface 20A to the foil or base surface 18A,corresponding to the surface 18 of FIGS. 1-3.

Referring now to FIG. 6, there is shown another alternate embodiment ofthe present invention in which composite pads 10B are formed by seriesof brackets 12B constructed so as to be connected together at the edgesof the base portions 13B thereof so as to form creases 16B which permitthe facile separation of the adjacent brackets. Attached directly to thebase portions 13B by bonding are mesh surfaces 20B, as is shown in FIG.7. However, in the embodiment of FIGS. 6 and 7, the shielding effectprovided by the wider foil or base portion 18, 18A of FIGS. 1-5 is notpresent, so that the device of FIGS. 6 and 7 while not permitting theadhesive to pass through the base as is done in U.S. Pat. No. 3,932,940,for example, suffers from the disadvantage of permitting the adhesive,if an excessive amount is used during the process of attachment, tocontact the bracket 12B directly, thereby necessitating its subsequentremoval by the orthodontist, with the attendant difficulties heretoforedescribed.

Referring now to FIG. 8, there is shown another alternate embodiment ofthe present invention in which a strip of brackets 10C have bodyportions 12C which are integral with base portions 13C. The baseportions 13C are connected together at creases 16C. The brackets 10C, asis shown in FIG. 9, have porous tooth-abutting mesh surfaces 20C of thesame type as are utilized in the previous embodiments. In the embodimentof FIGS. 8 and 9, the base portions 13C, including the body portion 12C,may be formed by any conventional process prior to bonding the meshportion 20C thereto. Alternatively, the mesh may be bonded to the baseportion prior to forming, by stamping, machining, extruding, or the likeof the bracket portion 12C on the base portion 13C. In either event, thebase portion 13C terminates in a porous tooth-abutting surface 20C,opposite which the base portion 13C is adapted to have an orthodonticappliance extend outwardly therefrom.

Referring now to FIG. 10, there is shown a portion of mesh 24 for useaccording to the preferred embodiment of the invention. As will be seenin FIG. 10, the mesh 24 consists of individual mesh elements 28 in alattice arrangement, onto which flats 30 have been formed in order toprovide a greater interface surface area between the mesh and the baseportion of the composite base to be formed. The process of forming theseflats will be described hereinafter with respect to FIGS. 11 through 16.

Referring to FIGS. 13 and 14, there is shown a strip of partially formedcomposite pads 10D, each consisting of the metal foil pad 18 which isuniformly secured to the metal mesh pad 20 by bonding at each interfacebetween the mesh and the foil, preferably by the process known assintering or diffusion bonding. Each composite pad 10D preferably iscontoured both laterally and longitudinally as shown in FIGS. 2 and 3 tofit the tooth's curved surface. The foil pad 18 provides a smooth topsurface for the composite pad which is suitable for attachment of manydifferent types of orthodontic appliances by spot welding, brazing, orthe like. The mesh pad 20 provides a surface suitable for use withappropriate cement, such as a carboxylate cement, for direct bonding ofthe composite pad to the surface of a tooth.

To produce the composite pads 10D shown in FIGS. 10 and 11, a strip ofmetal foil 22, as shown in FIG. 15, and a strip of metal mesh material24 are used. Preferably, in order to assure satisfactory bonding betweenthe mesh strip 24 and the foil strip 22 by increasing the total area ofthe interface between the foil and individual members 28 of the mesh(see FIG. 11), the mesh strip 24, either alone or with the foil strip22, is passed through a press, which may consist of a series of rollers(not shown), to provide flats 30 on the circular cross-section of theindividual members 28 of the mesh at individual interfaces 32 (see FIG.11) between the foil 22 and mesh 24. The foil strip 22 and mesh strip 24are then heat treated in a controlled atmosphere to a temperature whichproduces sintering bonds 34 between the mesh strip 24 and the foil strip22 at the interfaces 32 between the mesh members 28 and the foil 22 aswell as between the individual mesh members 28, the process being knowncommercially as diffusion bonding. Pressure is applied to the foil strip22 and mesh strip 24 as shown in FIG. 16 during the sintering process toassist in the bonding, if desired. In certain applications, thispressure is sufficient to form flats on the mesh, thus eliminating theprior rolling step if otherwise used.

The process of sintering produces a bond between the two metallic strips22, 24 without actually having any substantial liquid flow between themetals, in order to keep all interstices 36 of the mesh pad 20substantially free of any such material, thereby retaining the meshstructure intact for adhesive bonding purposes. The sintering produces abond 34 between the mesh and the foil as illustrated in FIG. 11. In FIG.11 the foil 22 is fixed to the mesh 24 at the interface flats 30 on theindividual strands 28 of the mesh to provide a mesh to foil bond 34 ofgreat strength, while mesh strand to mesh strand bonding 34A increasesthe rigidity of the composite pad over a composite pad with only a meshto foil bond.

Both the foil strip 22 and the mesh strip 24 are preferably stainlesssteel. The foil may typically be of 0.007 inch thickness. The mesh ispreferably 100 squares per inch, with a wire diameter of about 0.0045inches, although other meshes may be suitable in order to obtaincomplete bonding of all the mesh pads to be produced from the foil-meshstrip. The rolling and pressing may be repeated successively severaltimes, if required, to provide the proper surface area of the flats onthe mesh strip 24 for diffusion bonding.

The composite pads preferably are not formed individually, but rather ina multiple strip by cutting, stamping or some other suitable operationon the flat foil-mesh strip after bonding to provide the strip 10D asshown in FIGS. 13 and 14. For purposes of handling, the strips ofcomposite pads can be simultaneously formed with the individual padjoined at the edges as indicated at 16. These strips of pads are nowsuitable for handling for attachment of various orthodontic appliances.Alternatively, individual separate pads can be provided in variousassortments of sizes and contours to provide for the differences insizes and shapes of the various teeth.

In FIG. 12, there is shown an alternate embodiment of bonding, in whichthe individual strands 28 of the metal are not flattened. The bonding isshown at 34B, as brazing or the like, although sintering or diffusionbonding may also be used, just as brazing may be used in the embodimentof FIG. 11. As will be seen, the individual interface surface areasbetween the mesh and the foil are much less than in the preferredembodiment of FIG. 11. Such bonding may be accomplished by platingeither the foil 22 or the mesh 24, or both, with a very thin coating ofa suitable material, such as gold or nickel, before sintering. A verytiny fillet of braze material results at each point of contact betweenthe foil and mesh during the heating of the two metals. This method canbe practical and economical as the braze will flow in a controlledatmosphere without flux. The brazing may be accompanied by sintering, ifdesired.

Brazing may also be provided by sandwiching a very thin sheet of brazingmaterial, such as a nickel alloy, between the foil 22 and the mesh 24and then sintering in a controlled atmospheric furnace. Care must beexercised to avoid an excess of brazing material between the foil 22 andthe mesh 24, which, otherwise, will fill the interstices 36 between themesh and the foil, thereby reducing the adhesion capability of thecomposite pad to the tooth.

The composite pads 10, 10A, 10B, 10C, 10D, having metal bases,preferably sintered or diffusion bonded to the mesh, provide superiororthodontic apparatus for direct bonding of appliances to the teeth. Toapply the appliance to the tooth, the tooth is first etched with asuitable etching compound such as phosphoric acid and then an adhesiveis smoothed onto the etched tooth enamel. The pad carrying theorthodontic appliance is then pressed onto the bonding material, causingthe bonding material to flow into the interstices 36 of the poroustooth-abutting face, around the indivdual strands 28 to create a bond tothe tooth which is many times the bond strength of previous pads whenbonded directly to a tooth. While FIGS. 1-9 illustrate attachment of anedgewise bracket, the composite pad may be used with other devices, suchas light wire brackets, buccal tubes, hooks, and the like to provide thestrongest possible uniform bond of orthodontic appliance to the tooth bydirect bonding.

The particular temperature and atmosphere used during the sintering ordiffusion bonding process depends, of course, upon the particularmaterials selected for producing the mesh strip and base bond. As thesintering process consists of heating the materials to be bonded to atemperature below the flow temperature, it is imperative that thecharacteristic of the particular materials being used should be known.In the process of sintering two materials, there is a temperature atwhich the materials become somewhat fluid, but it is preferred that inthe practice of the present invention that such temperatures not bereached, thereby avoiding any substantial flow of material.

In the sintering process, the mesh portion of the composite pad is fixedto the base portion, thereby greatly increasing the rigidity of thecomposite pad over the base portion alone, particularly in theembodiment of FIGS. 1-3, in which a foil base is used. The rigidity ofthe composite pad is also increased by the individual members of themesh portion becoming sintered to one another at the points of contactbetween cross-members. Thus, the mesh portion alone, after sintering, ismuch more rigid than prior to sintering, and the composite pad providesa structure which can be formed, during manufacture, to conform to thevarious contours of the appropriate portions of different teeth. Once soformed, the composite pad retains the desired contour, even duringattachment of the orthodontic appliance, if the appliance has not beenattached prior to shaping the pad to the desired tooth conformingcontour. By selecting one of a series of shaped pads which isappropriate for the particular tooth to which the appliance is to befixed, the orthodontist need not himself be concerned with shaping thepad. Thus, by maintaining a supply of various pad sizes and contours,the orthodontist can readily meet the requirements of a particularpatient for the entire orthodontic treatment.

The foregoing description of the preferred form of this embodiment ofthe invention provides for the production of "flats" on the mesh priorto or during bonding. While such an embodiment is preferred, the meshcan be satisfactorily bonded to the base without the utilization offlats, provided that bonds at substantially all of the individualinterfaces between the mesh and the base are achieved. Also, while theattachment of the orthodontic appliance to the base is describedheretofore as occurring after the bonding of the mesh to the base, theappliance can be attached to the base in serial fashion prior tobonding, if desired. Such a variation in the method of the presentinvention produces a pad which avoids the damage to part of the meshsurface which may otherwise occur during the subsequent attachment tothe appliance to the pad, particularly if spot welding is used.

While, embodiment described utilizes stainless steel, other metals canbe used if desired. Also, non-metallic meshes can be used, provided thata satisfactory bonding process is available to bond the mesh to thebase. In its broadest sense, the pad of the present invention has a basewith a porous tooth-abutting face which terminates in a non-porousportion. However the formation of the porous surface is not limited tothe utilization of meshes. For example, small stainless steel spheres,about 0.006 inches in diameter, can be used in place of the mesh and oneor more layers bonded directly to each other and the base to provide theporous surface for attachment of the composite pad to the tooth. Theterm mesh, therefore, contemplates porous tooth-abutting surfaceportions with interconnected interstitial passages generally, and is notnecessarily limited to the use of screen type meshes unless specificallyso defined in the claims hereof.

Referring now to FIG. 17, there is shown, in cross-section, anorthodontic device 40 including a base 42 and a bracket portion 44. Thebase 42 is shown in section and has a central portion 46 and a pair ofshoulders 48. Thus, the orthodontic device 40 shown in FIG. 17corresponds generally to the device 10 shown in FIGS. 4 and 5 in overalldimensions. Alternatively, the orthodontic device 40 can have a narrowerbase portion, such as is generally shown with respect to the orthodonticappliance 10B of FIGS. 6 and 7. As seen in FIG. 17, the base 42 has aseries of pore-like cavities or recesses 50 forming a tooth-abuttingsurface 52 thereof. The tooth abutting surface 52 is porous andterminates in an upper base portion 54 which is non-porous and which isadapted to have the actual orthodontic appliance in this case, thebracket portion 44, extend outwardly therefrom. The device 40 may beformed by casting, with the porous surface 52 formed at the time ofcasting of the bracket portion 40 casting or, alternatively, the poroussurface 52 may be formed subsequent to forming the base portion 42, bychemical etching, drilling, or any other comparable method. Thus, theappliance 40 of FIG. 17 has a porous tooth-abutting surface withinterstitial spaces adapted to receive an adhesive to permit theadhesive to pass into, but not through, the base 42. The adhesive bondsthe base 42 and thus the appliance 40 to the tooth.

FIG. 18 illustrates a partial sectional view of an alternate embodimentof a cast unitary structure orthodontic appliance of the general typedescribed with respect to FIG. 17. However, the device of FIG. 18 has abase portion 60 with a porous face 62 having a mesh-like or wovenappearance generally similar to that shown with respect to the devicesof FIGS. 1 through 16. Thus, the base portion 60, in addition to theporous tooth-abutting face 62, has a non-porous portion 64 from whichthe porous face 62 extends outwardly for contact with the tooth.However, the porous face 62 has individual members 28A, generallysimilar to the members 28 of FIGS. 11, 12, but formed differently. Theappliance of FIG. 18 is formed by the "lost wax" method of casting, inwhich a model of the appliance is made of wax or similar material. Amold is then formed about the wax model and the wax removed by heatingor a similar process. This method produces a mold cavity which conformsto the precise configuration of the appliance to be formed. Hollowportions conform to the individual crossing members 28A which are toform the porous surface 62. By having mold material conforming tointerstices 36A in the appliance of FIG. 18. The mold cavity is thenfilled with molten metal which is to form the appliance, and aftersolidification, the mold material is removed from around the appliance.Mechanical means such as sand blasting or chemical means such as dippingin a caustic solution, or combinations of mechanical and chemical meansmay be utilized for this purpose.

FIG. 19 illustrates the base portion 70 of an alternate embodiment ofcast orthodontic appliance according to the present invention, having aporous surface 72 formed differently from that described with respect toFIG. 18. The porous surface 72 consists of individual crossing members28B which are formed of a screen or mesh generally similar to thatdescribed in FIGS. 1 through 16. The appliance 70 has a non-porous castportion 74. The members 28B are in the mold at the time of casting. Thecasting process results in some melting of the members 28B in the moldbetween the points of contacts 76 between members 28 and the moltenmaterial which is to form the solid base portion 74. When the castinghas cooled, the appliance shown in FIG. 19 is removed from the mold asdescribed above with the members 28 thereby fixed to the base portion74, thereby providing a unitary structure having a porous tooth-abuttingsurface 72 terminating in a non-porous 74 which is adapted to have anorthodontic appliance extend outwardly therefrom away from thetooth-abutting surface 72. Interstices 36 in the porous surface 72permit adhesive utilized to attach the appliance shown in FIG. 19 to atooth to enter into the porous surface 72, while the non-porous portion74 prevents the adhesive from passing through the base 70.

FIG. 20 shows a fragmentary cross-sectional view of a modification ofthe embodiment illustrated in FIG. 17. In FIG. 20, an orthodontic device40A, which is generally the same as the device 40 of FIG. 17, has a base42A, into which a series of pore-like cavities or recesses 50A extend toform a tooth-abutting surface 52A. The cavities 50A differ from thecavities 50 of the device 40 of FIG. 17 in being slightly undercut asthe cavities 50A extend away from the tooth-abutting surface 52A, thusforming bulb-like recesses. These bulb-like recesses provide, inconjunction with the adhesive used to attach the device 40A to thetooth, a greater holding power than exists with the generallycylindrical recesses 50 of the embodiment of FIG. 17 which do not havethe undercut configuration. While the device 40A can be formed either bycasting or chemically etching the recesses 50A in the base 42A, achemical etching process is preferred.

The foregoing descriptions of the preferred embodiments are given by wayof description only, and are not intended to limit the scope of theinvention except in accordance with the claims hereof.

The invention claimed is:
 1. Apparatus for use in the practice oforthodontics by being fixed to a tooth by means of an adhesivecomprising:a base having a first portion which is porous withinterstitial passages and an outer tooth-contour conforming face and asecond co-extensive portion which is non-porous, said first portionterminating in said second portion, said second portion having anorthodontic appliance extending outwardly therefrom remote from saidfirst portion; and in which the first and second portions are formedsimultaneously by casting, whereby said adhesive may enter the poroustooth-abutting surface portion but cannot pass through the base to reachthe orthodontic appliance.
 2. Apparatus for use in the practice oforthodontics by being fixed to a tooth by means of an adhesivecomprising:a composite base having a first portion which is mesh-likewith an outer tooth-contour conforming face and a second co-extensiveportion which is impervious to the adhesive, said first portionterminating in said second portion; and an orthodontic applianceextending outwardly from the second portion remote from said firstportion; and in which the first portion is bonded to the second portionby the second portion being cast upon the first portion, whereby saidadhesive may enter the mesh-like tooth-abutting surface portion butcannot pass through the base to reach the orthodontic appliance.
 3. Theapparatus of claim 2, and in which the first portion is about 100 mesh.4. An orthodontic appliance formed by:contacting a metal mesh materialwith a metal foil along one surface of the mesh so that said meshsurface forms individual interfaces with one surface of the foil;bonding the metal mesh material to the metal foil at the individualinterfaces therebetween to form a bracket pad; positioning anorthodontic bracket on the foil side of said paid; and attaching saidbracket to said pad.
 5. Apparatus for use in the practice oforthodontics by being fixed to a tooth by means of an adhesivecomprising:a cast base having a first portion with an outertooth-contour conforming face in which are formed a plurality ofindividual bulb-like adhesive receiving recesses, each of which opensonto and is enclosed by the tooth-contour conforming face, and a secondportion which is impervious to the adhesive, said first portionterminating in said second portion; and an orthodontic applianceextending outwardly from the second portion opposite said tooth-contourconforming face, whereby said adhesive, when applied to thetooth-abutting surface portion may enter the bulb-like recesses butcannot pass through the base to contact the orthodontic appliance. 6.Apparatus for use in the practice of orthodontics by being fixed to atooth by means of an adhesive comprisinga base having a first portionwhich is porous with an outer tooth-contouring conforming face, and asecond portion which is non-porous, said first portion terminating insaid second portion, and said second portion having an orthodonticappliance extending outwardly therefrom remote from the said firstportion; and in which the second portion has a base portion onto whichthe first portion is cast and the first portion is about 100 mesh,whereby said adhesive may enter the porous tooth-abutting surface butcannot pass through the base to reach the orthodontic appliance. 7.Apparatus for use in the practice of orthodontics by being fixed to atooth by means of an adhesive comprising:a base having a first portionwith an outer tooth-contour conforming face in which a plurality ofindividual bulb-like adhesive receiving recesses, each of which opensonto and is enclosed by the tooth-contour conforming face, are formed bychemical etching, and a second portion which is impervious to theadhesive, said first portion terminating in said second portion; and anorthodontic appliance extending outwardly from the second portionopposite said tooth-contour conforming face, whereby said adhesive, whenapplied to the tooth-abutting surface portion, may enter the bulb-likerecesses but cannot pass through the base to contact the orthodonticappliance.